Thin film removing device and thin film removing method

ABSTRACT

A thin film removing device and a thin film removing method are capable of removing straight parts of a thin film formed on a square substrate from corners of the substrate, and of suppressing the formation of mists. An approach stage  20  having flat stage plates  23  capable of being disposed substantially flush with the surface of a substrate M mounted on a support table  22  is positioned close to the substrate M mounted on the support table  22 . Removing nozzles  30  jet a solvent toward edge parts of the substrate M and suck a solution produced by dissolving part of the resist in the solvent while the removing nozzles  30  are moved along side edges of the substrate M and the approach stage  20  disposed close to the substrate M. Thus, the removing nozzles  30  jet the solvent uniformly over the edge parts and corners of the substrate M and suck the solution without changing modes of jetting the solvent and sucking the solution. Consequently, straight parts of a thin film formed on the square substrate M can be removed from the corners of the substrate M, and the formation of mists can be suppressed.

This present application is a Divisional Application of Ser. No.10/841,548, filed May 10, 2004, now U.S. Pat. 7,332,056, which claimsthe benefit from the prior Japanese Patent Application No. 2003-136411filed May 14, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin film removing device and a thinfilm removing method for removing thin films from glass substrates forphotomasks (reticles), flat display panels for flat panel displays(FPDs) and the like.

2. Description of the Related Art

Generally, a photomask fabricating process and a liquid crystal displayfabricating process uses the photolithographic technique similar to thatapplied to semiconductor device fabrication for forming, for example,thin ITO films (indium tin oxide films) and circuit patterns. Forexample, the photolithographic technique applies a liquid resist to thesurface of a substrate by a liquid resist application process to form aresist film on the substrate, exposes the resist film to an image of acircuit pattern by an exposure process, and forms a circuit pattern inthe resist film by a developing process.

A spin coating method is widely employed in the liquid resistapplication process. The spin coating method holds a substrate on a spinchuck placed in a processing vessel, drops a liquid resist prepared bydissolving a photosensitive resin in a solvent on the substrate androtates the spin chuck holding the substrate at a high rotational speedto form a resist film of a uniform thickness on the substrate byspreading the liquid resist over the surface of the substrate bycentrifugal force.

When the resist film is formed by the liquid resist application processemploying the spin coating method, there is some possibility that theuniformity of the thickness of the resist film deteriorates with timeeven if the resist film has the uniform thickness immediately afterformation. For example, the liquid resist covering an edge part of thesurface of the substrate is caused to rise by the agency of surfacetension to increase part of the resist film covering the edge part ofthe surface of the substrate when centrifugal force disappears due tothe stop of the spin chuck. In some cases, the liquid resist dropped onthe upper surface of the substrate flows over the edges of the substrateto an edge part of the lower surface of the substrate and forms anunnecessary resist film on the edge part of the lower surface of thesubstrate.

If the resist film is formed on the edge part of the substrate in anirregular thickness, unnecessary parts of the resist film on the edgepart of the substrate cannot be completely removed and remain on thesubstrate when a circuit pattern or the like formed in the resist filmis developed. It is possible that the unnecessary remaining parts of theresist film affect adversely to the following processes or come off inparticles during the transportation of the substrate.

Therefore, as mentioned in Patent document 1, namely, JP-A No.2001-198515 (paragraph numbers 0061 to 0066, 0083 and 0084, FIGS. 3, 4,6 and 10), the part of the resist film on the edge part of the substrateis removed by a thin film removing device called an edge remover. Thethin film removing device has a thin film removing head, namely, a thinfilm removing means, to remove a part of the resist film from an edgepart of the substrate. The thin film removing head moves along the edgesof the substrate, jets a mixture of a solvent and a pressurized inertgas, such as nitrogen gas (N₂ gas) to dissolve parts of the resist filmon edge parts of the substrate in the solvent and to remove the parts ofthe resist film in a resist solution, and sucks the resist solution.

When carrying out the conventional thin film removing method, however,the mixture of the pressurized gas and the solvent spreads at thecorners of the substrate in a range wider than that in which thepressurized gas spreads at the sides of the substrate, changing the flowof the pressurized gas for spraying the solvent and condition forsucking the resist solution. Consequently, the mixture cannot be jettedlinearly, mists are formed, and corners of the resist film bulge inprotrusions. Since a low suction acts on the corners of the resist film,mists formed around the corners cannot be satisfactorily sucked.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoingcircumstances and it is therefore an object of the present invention toprovide a thin film removing device and a thin film removing methodcapable of removing straight parts of a thin film formed on a squaresubstrate, from edge parts and corners of the substrate, and ofsuppressing the formation of mists.

A thin film removing device according to the present invention forremoving unnecessary parts of a thin liquid film formed on a surface ofa square substrate from edge parts of the surface of the substrate byjetting a solvent against the edge parts of the surface of the substrateincludes: a support table on which the substrate is mounted; an approachstage disposed near edges of the substrate mounted on the support table,and having flat approach parts having surfaces capable of being extendedsubstantially flush with the surface of the substrate; thin filmremoving means capable of jetting a solvent toward edge parts of thesubstrate mounted on the support table and of sucking a solutionproduced by dissolving part of the thin liquid film in the solvent; anda thin film removing means moving mechanism for moving the thin filmremoving means along edges of the substrate and the flat approach partsof the approach stage adjacent to edges of the substrate.

The thin film removing device according to the present invention mayfurther include a substrate holding means for transferring a substrateto and receiving the same from the support table, capable of movingvertically and of turning through at least an angle of 90° in ahorizontal plane.

In the thin film removing device according to the present invention, theapproach stage may be of any type provided that the approach stage canbe disposed near the edges of the substrate mounted on the support tableand has flat approach parts having surfaces capable of being extendedsubstantially flush with the surface of the substrate. For example, theapproach stage may be provided with walls respectively rising up fromthe flat approach parts so as to define narrow spaces together with thethin film removing means.

In the thin film removing device according to the present invention, atleast the surfaces of the flat approach parts of the approach stage maybe coated with a water-repellent film, or each of the flat approachparts may be provided with small holes, and the small holes may beconnected to a suction pipe.

The thin film removing device according to the present invention mayfurther include an approach stage moving mechanism capable of moving theapproach stage toward and away from the support table, width measuringmeans for measuring the width of the substrate mounted on the supporttable, and a control means for controlling the approach stage movingmechanism on the basis of signal provided by the width measuring means.

A thin film removing method according to the present invention isintended to remove unnecessary parts of a thin liquid film formed on asurface of a square substrate from edge parts of the surface of thesubstrate by jetting a solvent against the edge part of the surface ofthe substrate.

A thin film removing method according to the present invention includesthe steps of: mounting a substrate on a support table; positioning anapproach stage having flat approach parts with the flat approach partspositioned close to edges of the substrate mounted on the support tableand surfaces of the flat approach parts extending substantially flushwith a surface of the substrate mounted on the support table; andjetting a solvent toward edge parts of the substrate mounted on thesupport table and sucking a solution produced by dissolving part of thethin film in the solvent by thin film removing means while the thin filmremoving means is moved along end edges of the substrate.

A thin film removing method according to the present invention includesthe steps of: mounting a substrate on a support table; measuring widthof the substrate by moving width measuring means from a positioncorresponding to one side of the substrate mounted on the support tableto a position corresponding to the other side of the same; moving anapproach stage having flat approach parts, and capable of beingpositioned with surfaces of the flat approach parts substantially flushwith the surface of the substrate mounted on the support table, on thebasis of a width signal provided by the width measuring means to aposition close to the edges of the substrate mounted on the supporttable; and removing unnecessary parts of a thin film formed on thesubstrate from edge parts of the substrate by moving thin film removingmeans capable of jetting a solvent toward the edge parts of thesubstrate mounted on the support table and of sucking a solutionproduced by dissolving part of the thin film in the solvent along edgesof the substrate and the approach stage.

A thin film removing method according to the present invention includes:a first substrate mounting step of mounting a substrate on a supporttable; a first width measuring step of measuring width of the substratemounted on the support table by moving width measuring means from aposition corresponding to one side of the substrate to a positioncorresponding to the other side of the same; a first approach stagepositioning step of positioning an approach stage having flat approachparts respectively having surfaces capable of being extendedsubstantially flush with the surface of the substrate such that the flatapproach parts are positioned respectively close to edges of thesubstrate on the basis of a signal provided by the width measuringmeans; a first thin film removing step of jetting a solvent toward edgeparts of the substrate and sucking a solution produced by dissolvingpart of the thin film in the solvent by thin film removing means whilethe thin film removing means is moved along edges of the substrate andthe approach stage; a directional position changing step of lifting upthe substrate from the support table, turning the substrate through 90°in a horizontal plane to change directional position of the substraterelative to the support table, and mounting the substrate again on thesupport table; a second width measuring step of measuring width of thesubstrate mounted on the support table by moving the width measuringmeans from a position corresponding to one side of the substrate towarda position corresponding to the other side of the same; a secondapproach stage positioning step of positioning the approach stage havingflat approach parts respectively having the surfaces capable of beingextended substantially flush with the surface of the substrate such thatthe flat approach parts are positioned respectively close to edges ofthe substrate on the basis of a signal provided by the width measuringmeans; and a second thin film removing step of jetting the solventtoward edge parts of the substrate and sucking the solution by the thinfilm removing means while the thin film removing means is moved alongthe edges of the substrate and the approach stage.

According to the present invention, the approach stage having the flatapproach parts having the surfaces capable of being extendedsubstantially flush with the surface of the substrate is positioned nearthe edge parts of the substrate mounted on the support table, and thesolvent is jetted toward the edge parts of the substrate mounted on thesupport table and the solution is sucked by the thin film removing meanswhile the thin film removing means are moved respectively along the edgeparts of the substrate and the approach stage positioned near the edgeparts of the substrate by the thin film removing means moving mechanism.Thus, the solvent can be uniformly distributed over the sides and thecorners of the substrate and the solution can be sucked from a spacearound the sides and the corners of the substrate by the thin filmremoving means without changing conditions for jetting the solvent andsucking the solution. Consequently, straight parts of the thin filmformed on the square substrate can be removed from the corners of thesubstrate and the formation of mists can be suppressed.

According to the present invention, the thin film removing deviceincludes the substrate transfer means for transferring the substrate toand receiving the same from the support table, capable of movingvertically and of turning in the angular range of at least 90° in ahorizontal plane. The substrate can be lifted up and turned through 90°by the substrate transfer means after removing parts of the thin filmfrom edge parts along the opposite edges of the substrate, and then thesubstrate is mounted again on the support table to remove parts of thethin film from edge parts along the rest of the sides of the substrate.Thus, parts of the thin film can be removed from the entire edge partsof the substrate. The substrate can be transferred between thevertically movable substrate transfer means and a substrate carryingmeans for carrying the substrate.

According to the present invention, the approach stage has the wallsrising up from the flat approach parts and defining the narrow spacestogether with the thin film removing means and thereby the suction ofthe thin film removing means can be enhanced. Consequently, parts of thethin film can be efficiently removed from the corners of the substrate.

According to the present invention, the water-repellent film formed atleast on the surface of the flat approach parts of the approach stagemakes the adhesion of the solvent to the flat approach parts of theapproach stage difficult. Consequently, formation of particles due tothe adhesion of the solvent to the surfaces of the flat approach partsand the separation of the dried solvent from the surfaces of the flatapproach parts can be suppressed.

According to the present invention, the approach stage can be positionedas close as possible to the substrate or can be disposed in contact withthe substrate by moving the approach stage toward the support table bythe approach stage moving mechanism. Thus, changes in the condition ofjetting the solvent and that of sucking the solution at the boundarybetween the substrate and the approach stage can be reduced, and thethin film can be further efficiently removed. Since the width of thesubstrate mounted on the support table is measured by the widthmeasuring means by moving the thin film removing means from one to theother end of the substrate, and the approach stage moving mechanism iscontrolled by a control signal provided by the control means on thebasis of a signal provided by the width measuring means, the approachstage can be disposed near or can be brought into contact with thesubstrate in an optimum state, taking into consideration the size of thesubstrate and dimensional errors in the substrate. Consequently, thethin film can be efficiently removed without being affected by the sizeof the substrate and dimensional errors in the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a resist film forming/removing systememploying a thin film removing device according to the presentinvention;

FIG. 2( a) is a schematic plan view of a thin film removing device in afirst embodiment according to the present invention;

FIG. 2( b) is an enlarged plan view of a part I in FIG. 2( a);

FIG. 3 is a schematic side elevation of the thin film removing device inthe first embodiment;

FIG. 4( a) is a sectional view of a resist removing nozzle according tothe present invention;

FIG. 4( b) is an enlarged sectional view of a part II in FIG. 4( a);

FIG. 5 is a perspective view of the resist removing nozzle and anapproach stage according to the present invention;

FIG. 6 is a perspective view of a chuck and the approach stage accordingto the present invention;

FIG. 7( a) is a perspective view of an approach stage in a modificationof the approach stage according to the present invention;

FIG. 7( b) is an enlarged sectional view taken on the line III-III inFIG. 7( a);

FIG. 8( a) is a perspective view of an approach stage in anothermodification of the approach stage according to the present invention;

FIG. 8( b) is an enlarged sectional view taken on the line III-III inFIG. 8( a);

FIG. 9 is a flow chart of a thin film removing method according to thepresent invention to be carried out by the thin film removing device inthe first embodiment;

FIG. 10 is a schematic plan view of a thin film removing device in asecond embodiment according to the present invention;

FIG. 11 is a flow chart of a thin film removing method according to thepresent invention to be carried out by the thin film removing device inthe second embodiment;

FIG. 12 is a perspective view of a resist-removing nozzle and anapproach stage in a first modification of the resist removing nozzle andthe approach stage shown in FIG. 5; and

FIG. 13 is a perspective view of a resist removing nozzle and anapproach stage in a second modification of the resist-removing nozzleand the approach stage shown in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described withreference to the accompanying drawings. A resist film forming/removingsystem employing a thin film removing device according to the presentinvention will be described.

FIG. 1 is a schematic plan view of the resist film forming/removingsystem, FIG. 2( a) is a schematic plan view of a thin film removingdevice in a first embodiment according to the present invention, FIG. 2(b) is an enlarged plan view of a part I in FIG. 2( a) and FIG. 3 is aschematic side elevation of the thin film removing device in the firstembodiment.

A resist film forming/removing system has a casing 1, a liquid resistapplication unit 2 placed in the casing 1, and a thin film removing unit3 placed adjacent to the liquid resist application unit 2 in the casing1.

The liquid resist application unit 2 includes a rotating cup 4 servingas a processing vessel, a spin chuck 5 for supporting a photomasksubstrate M (hereinafter, referred to simply as “substrate M”) thereonby suction, and a resist-removing nozzle 6 for dropping a liquid resistonto the substrate M from above the center of the substrate M.

The resist nozzle 6 of the liquid resist application unit 2 is moved toa position above the center of the substrate M, the liquid resist isdropped from the resist nozzle 6 onto the substrate M, and then the spinchuck 5 is rotated at a high rotational speed to spread the liquidresist over the substrate M by centrifugal force. Thus, a thin liquidresist film of a uniform thickness is formed over the entire surface ofthe substrate M. Such a technique for applying the liquid resist to thesubstrate M while the substrate is rotating is applied also to a processof forming a circuit pattern on a semiconductor wafer. It is difficultto form a uniform liquid resist film on the substrate M because thesubstrate M is square (rectangular), while the semiconductor wafer iscircular. Since the four corners of the substrate M are distant from thecenter of the substrate, the four corners evolve at a considerably highcircumferential speed. Therefore, it is possible that adverse turbulentair currents are generated around the four corners of the substrate M.The volatilization of a solvent contained in the liquid resist must besuppressed to the least possible extent and the liquid resist must beconstantly spread to spread the liquid resist uniformly to the cornersof the substrate M. In this liquid resist application unit 2, thesubstrate M is sealed in the rotating cup 4, and is rotated togetherwith the rotating cup 4 to prevent the volatilization of the solvent andthe generation of turbulent air currents.

The substrate M thus coated with a liquid resist film is carried by apair of carrying arms 8, namely, substrate carrying means, capable ofmoving along guide rails 7 to the thin film removing unit 3.

The thin film removing unit 3 has a support table 22 for supporting thesubstrate M thereon, a chuck 10, namely, a substrate transfer means fortransferring the substrate M to and receiving the same from the supporttable 22, an approach stage 20 disposed near opposite sides of thesubstrate M mounted on the support table 22, resist-removing nozzles 30(hereinafter, referred to simply as “removing nozzles 30”), namely, thinfilm removing means, and a nozzle moving mechanism 40 for moving theremoving nozzles 30.

Referring to FIGS. 3 and 6, the chuck 10 has a chuck body 11 forsupporting the substrate M thereon, a support shaft 12 supporting thechuck body 11, and a chuck operating mechanism 50 interlocked with thesupport shaft 12. The chuck operating mechanism 50 moves the chuck body11 vertically, i.e., along the Z-axis, and turns the chuck body 11 in ahorizontal plane, i.e., an XY-plane. The chuck body 11 has a rectangularhub 11 b joined to the upper end of the support shaft 12 and having theshape of a flat plate, four arms 11 b radially extending from thecorners of the hub 11 a and having the shape of a flat strip, and framemembers 11 c extending between the outer ends of the adjacent arms 11 b,respectively, and having the shape of a flat strip. The joints of theframe members 11 c are beveled. Four support pins 13 are attached to thefour beveled corners of the chuck body 11 to support the substrate Mwith a narrow space formed between the upper surface of the chuck body11 and the substrate M. Four pairs of holding pins 14 (eight holdingpins 14) are attached to the four beveled corners of the chuck body 11.

Referring to FIGS. 2, 3, 5 and 6, the approach stage 20 has two flatapproach plates 23 set in a horizontal position on holding member 22attached to upper ends of four support rods 21 set upright on a base 9,and fastened to the holding members 22 with bolts 29. Each of theholding members 22 is provided with a positioning pin 22 a that comesinto contact with a side of the substrate M, and a proximity seat 22 bfor supporting the substrate M such that a narrow space of, for example,0.2 mm is formed between the upper surface of the support table 22 andthe substrate M (FIG. 3).

The substantially rectangular flat approach plates 23 of the approachstage 20 have upper surfaces substantially flush with the upper surfaceof the substrate M mounted on the support table 22. The flat approachplates 23 are adjacent to the sides of the substrate M. The end surfacesof the flat approach plates 23 are flush with the end surfaces of thesubstrate M, respectively. Gaps between the approach stage 20 and thesubstrate M are 1.0 mm or below. As shown in FIG. 2( b), opposite endparts of the inner edge of each of the flat approach plates 23 areconcavely curved in a round edge R2 complementary to a convexly curvedround edge R1 of a rounded corner of the substrate M so that a gap ofthe same size as that between the side of the substrate M and a straightmiddle part of the flat approach plate 23. Preferably, at least thesurface of each flat approach plate 23 of the approach stage 20 iscoated with a water-repellent film 24 (FIG. 7( b)). The water-repellentfilms 24 formed on the surfaces of the flag approach plates 23 make itdifficult for a solvent, such as a thinner, used for removing a thinfilm (resist film) to adhere to the approach stage 20, and prevent theformation of particles due to the adhesion of the solvent to thesurfaces of the flat approach plates and the separation of the driedsolvent from the surfaces of the flat approach plates. The approachstage 20 has a width equal to or greater than the width of a spacebetween the removing nozzles 30.

Referring to FIG. 4, each of the removing nozzles 30 has a nozzle head31 of a substantially U-shaped cross section provided with a groovedefined by an upper wall 32 and a lower wall 33 to receive an edge partof the substrate M. When the edge part of the substrate M is received inthe groove of the nozzle head 31, gaps of a thickness of, for example, 1mm are formed between the upper surface of the substrate M and the innerside surface of the upper wall 32, and between the lower surface of thesubstrate M and the inner surface of the lower wall 33, respectively.The nozzle head 31 is provided with solvent jetting holes 34 a and 34 bformed in the upper wall 32 and the lower wall 33, respectively. Asolvent, such as a thinner, is jetted through the solvent jetting holes34 a and 34 b toward the upper and the lower surface of the substrate M.The respective positions of the nozzle holes 34 a and 34 b aredetermined so that the solvent jetting holes 34 a and 34 b may notinterfere with each other. The nozzle holes 34 a and 34 b are connectedto a solvent tank 36 by a solvent supply pipe 35. A compressed gassource 38 is connected through a valve V1 to the solvent tank 36 by agas supply pipe 37 to supply a compressed gas, such as compressednitrogen gas, into the solvent tank 36. The solvent contained in thesolvent tank 36 is supplied by pressure to the solvent jetting holes 34a and 34 b by the pressure of the compressed gas. The solvent may besupplied to the solvent jetting holes 34 a and 34 b by a pump instead ofby the compressed gas, such as compressed nitrogen gas.

The upper wall 32 and the lower wall 33 of the nozzle head 31 areprovided with inert gas jetting holes 39 a and 39 b, respectively, andan inert gas passage 39 c connected to the inert gas jetting holes 39 aand 39 b. The inert gas jetting holes 39 a and 39 b are inclined so thatan inert gas jetted through the inert gas jetting holes 39 a and 39 bmay flow radially outward along the upper and the lower surface of thesubstrate M. An inert gas source 39A is connected through a valve V2 tothe inert gas passage 39 c by an inert gas supply pipe 39 d.

The upper wall 32 and the lower wall 33 of the removing nozzle 30 areconnected by a side wall 31 a. The side wall 31 a is provided with asuction hole 31 b. An exhaust pipe 31 c has one end connected to thesuction hole 31 b and the other end connected to an exhaust device, notshown.

Each removing nozzle 30 is slidably mounted on a guide rail 41 extendedparallel to the sides of the chuck 10 and the support table 22 on theouter side of the support table 22. The removing nozzle 30 is moved fromone to the other end of the side of the substrate M mounted on thesupport table 22 by a nozzle moving mechanism 40 including, for example,a stepping motor 42 and a timing belt 43. The nozzle moving mechanism 40may be, for example, a ball screw mechanism or a cylinder actuator.

The solvent is jetted toward edge parts of the substrate M through thesolvent jetting holes 34 a and 34 b, and the inert gas is jetted throughthe inert gas jetting holes 39 a and 39 b so that the inert gas flowsradially outward along the upper and the lower surface of the substrateas the removing nozzles 30 are moved along the opposite sides of thesubstrate M. Thus, parts of the resist film, formed on the edge parts ofthe substrate M are dissolved and removed. Since a suction is producedin the suction holes 31 b by the exhaust device, the solvent used fordissolving the parts of the thin film and a solution produced bydissolving the parts of the thin film in the solvent are sucked throughthe suction holes 31 b and are exhausted outside.

A resist-removing procedure for removing unnecessary parts of a resistfilm from edge parts of a substrate M will be described with referenceFIG. 3 and a flow chart shown in FIG. 9. A liquid resist film is formedon a substrate M by the liquid resist application unit 2. The carryingarms 8 carry the substrate M coated with the liquid resist film to thethin film removing unit 3, the chuck 10 is raised to receive thesubstrate M from the carrying arms 8. Then, the carrying arms 8 areretracted from the thin film removing unit 3. In step 9-1, the chuck 10is lowered to mount the substrate M on the support table 22 such thatthe substrate M is adjacent to the flat approach plates 23. In step 9-2,the removing nozzles 30 jetting the solvent and the inert gas andsucking gases around the removing nozzles 30 are moved continuously fromone of the flat approach plates 23 on one side of the substrate M to oneend of the substrate M, along opposite side edge parts of the substrateM, respectively, and from the other end of the substrate M to the otherflat approach plate 23 for a resist-removing process. Thus, parts of theresist film are removed simultaneously from the opposite side edge partsof the substrate M. Splash of the solvent by the flat approach plate 23on the starting side from which the removing nozzles 30 are started canbe prevented. Since the flat approach plates 23 are disposed close tothe opposite ends of the substrate M, respectively, the solvent can beuniformly jetted against the side edges and the corners of the substrateM and the solution can be sucked from a space around the side edges andthe corners of the substrate M by moving the removing nozzles 30 acrossthe flat approach plates 23 and along the side edges of the substrate Mwithout changing conditions for jetting the solvent and sucking thesolution. Consequently, straight parts of the thin film formed on thesubstrate M can be removed from the corners of the substrate M and theformation of mists can be suppressed.

The removing nozzles 30 are returned to their home positions after theparts of the resist film have been removed from the opposite side edgeparts of the substrate M. Then, in step 9-3, the chick operatingmechanism 50 raises the chuck 10 to lift up the substrate M from thesupport table 22 ({circle around (1)} in FIG. 3), turns the raised chuck10 through 90° in a horizontal plane ({circle around (2)} in FIG. 3),and lowers the chuck 10 to mount the substrate M again on the supporttable 22 ({circle around (3)} in FIG. 3). At this stage, the side edgeparts of the substrate M from which the parts of the resist film havebeen removed are positioned close to the flat approach plates 23,respectively. Subsequently, the resist-removing process is executedagain in step 9-4; the removing nozzles 30 are moved continuously fromone of the flat approach plates 23 on one side of the substrate M to oneend of the substrate M, along opposite side edges of the substrate M,respectively, and from the other end of the substrate M to the otherflat approach plate 23. Thus, parts of the resist film are removedsimultaneously from the other opposite side edge parts of the substrateM. Consequently, straight parts of the thin film formed on the substrateM can be removed from the corners of the substrate M and the formationof mists can be suppressed.

Subsequently, the removing nozzles 30 are returned to the homepositions, respectively, and are kept at the home positions for the nextcycle of the resist-removing process. Then, the chuck operatingmechanism 50 raises the chuck 10, the carrying arms 8 are moved into thethin film removing unit 3, and the thus processed substrate M istransferred from the chuck 10 to the carrying arms 8. Substrates aresubjected to the thin film removing process successively, and theforegoing steps are repeated to remove unnecessary parts of resist filmsfrom edge parts of the substrates.

The flat approach plates 23 of this thin film removing unit 3 have theshape of a flat strip. Each of the flat approach plates 23 may beprovided with an upright wall 25 on its upper surface as shown in FIGS.7( a) and 8(a) to form a narrow space between the removing nozzle 30 andthe flat approach plate 23. The narrow space formed between the removingnozzle 30 and the wall 25 enhances the suction produced in the suctionhole 31 b to suck efficiently the solvent used for the thin filmremoving process, the solution produced by the thin film removingprocess and mists.

The water-repellent film 24 formed at least on the surface of each flatapproach plate 23 of the approach stage 20 as shown in FIG. 7 makes itdifficult for the solvent used for the thin film removing process andthe solution produced by the thin film removing process to adhere to thea thinner, used for removing a thin film (resist film) to adhere to theapproach stage 20. Thus, the formation of particles due to the adhesionof the solvent to the surfaces of the flat approach plates 23 and theseparation of the dried solvent from the surfaces of the flat approachplates 23 can be suppressed, and the yield can be improved. As shown inFIG. 8( b), each of the flat approach plates 23 of the approach stage 20may be a hollow structure, small holes 36 of a diameter in the range ofabout 0.1 to 0.3 mm may be formed in an upper wall of the hollow flatapproach plate 23, a cavity formed in the hollow flat approach plate 23may be connected to an exhaust device, such as a vacuum pump 28 by asuction pipe 27 to remove the solvent and such adhering to the approachstage 20 by suction generated by operating the vacuum pump 28. Thus, theformation of particles due to the separation of the dried solvent fromthe surfaces of the flat approach plates 23 can be suppressed, and theyield can be improved. The adhesion of the solvent and such to the flatapproach plates 23 can be further surely prevented by formingwater-repellent films 24 on the walls provided with the small holes 26of the flat approach plates 23.

Removing nozzles and approach stages in modifications of those shown inFIG. 5 will be described with reference to FIGS. 12 and 13.

There are some cases where the solvent and such remain in gaps 100between the corresponding edges of the flat approach plates 23 and thesubstrate M. In such a case, it is possible that the solvent and suchare splashed over the resist film and erode the resist film. Removingnozzles and approach stages shown in FIGS. 12 and 13 are intended tosolve such problems.

First, a thin film removing device in a first modification of the thinfilm removing device shown in FIG. 2 will be described.

Each of flat approach plates 23 included in the thin film removingdevice in the first modification is provided in each of opposite endparts thereof with three through holes 102 of, for example, 2 mm indiameter. Each of the through holes 102 has one open end 102 a openingin an end surface of the flat approach plate on the side of the removingnozzle 30, and an open end 102 b opening in a side surface facing thegap 100 of the flat approach plate 23. The three through holes 102 arestraight and parallel to each other.

In the first modification shown in FIG. 12, the solvent and suchremaining in the gap 100 can be sucked through the open ends 102 a intothe through holes 102 in the direction of the arrows 104, and can beremoved through the open ends 102 b when the removing nozzles 30 movealong the end edges of the flat approach plates 23. Consequently, theadhesion of the solvent and such to the resist film and the erosion ofthe resist film by the solvent and such can be prevented.

A thin film removing device in a second modification will be describedwith reference to FIG. 13.

Each of flat approach plates 23 included in the thin film removingdevice in the second modification is provided in each of opposite endparts thereof with a through hole 106 of, for example, 2 mm in diameter.The through hole 106 has an outer open end 106 a opening in the outerside edge perpendicular to the end edge along which the removing nozzle30 moves, and an inner open end 106 b opening in the inner side edgefacing the gap 100. The through hole 106 is bent, and has bend, an outersection parallel to the moving direction of the removing nozzle 30 andextending between the outer open end 106 a and the bend, and an innersection inclined to the moving direction of the removing nozzle 30 andextending between the bend and the inner open end 106 b. A suction pipe108 has one end connected to the outer open end 106 a of the throughhole 106 and the other end connected to a suction device.

In the second modification shown in FIG. 13, the solvent and suchremaining in the gap 100 an be sucked into the through holes 106 and canbe sucked away through the outer open ends 106 a in the direction of thearrow 109 by suction produced by the suction device in the suction pipes108 connected to the outer open ends 106 a. Consequently, the adhesionof the solvent and such to the resist film and the erosion of the resistfilm by the solvent and such can be prevented.

FIG. 10 is a schematic plan view of a thin film removing device in asecond embodiment according to the present invention.

In the thin film removing device shown in FIG. 10, an approach stage 20is disposed in an optimum state taking into consideration the size of asubstrate M and dimensional errors in the substrate M to improve theefficiency of a resist-removing operation. The approach stage 20 can bemoved relative to a support table 22 by an approach stage movingmechanism 60. Each of removing nozzles 30 is provided with a sensor 70for measuring the width of the substrate M mounted on the support table22. The removing nozzles 30 are moved for scanning from one to the otherend of the substrate mounted on the support table 22 to measure thewidth of the substrate M. The sensors 70 sends detection signals to acentral processing unit 80 (hereinafter, abbreviated to “CPU 80”),namely, control means, the CPU 80 provides a control signal forcontrolling the approach stage moving mechanism 60 to adjust theposition of the approach stage 20 relative to the substrate M accordingto the width of the substrate M.

The thin film removing device in the second embodiment is identical inother respects to that in the first embodiment and hence parts of thesecond embodiment like or corresponding to those of the first embodimentare denoted by the same reference characters and the description thereofwill be omitted.

A resist-removing procedure to be carried out by the second embodimentwill be described with reference to FIG. 10 and a flow chart shown inFIG. 11. In step 11-1, the carrying arms 8 carry the substrate M coatedwith the liquid resist film to the thin film removing unit 3, the chuck10 receives the substrate M from the carrying arms 8, and the chuck 10is lowered to mount the substrate M on the support table 22. In step11-2, the nozzle moving mechanism 40 moves the removing nozzles 30 forscanning from one to the other side of the substrate M to measure thewidth of the substrate M by the sensors 70, and the sensors 70 senddetection signals to the CPU 80. In step 11-3, the CPU 80 provides acontrol signal to control the approach stage moving mechanism 60 toposition the approach state 20 such that the flat approach plates 23 arepositioned as close as possible to the side edges of the substrate M ordisposed in contact with the side edges of the substrate M.

Then, in step 11-4, the removing nozzles 30 jetting the solvent and theinert gas and sucking gases around the removing nozzles 30 are movedcontinuously from one of the flat approach plates 23 on one side of thesubstrate M to one end of the substrate M, along opposite side edges ofthe substrate M, respectively, and from the other end of the substrate Mto the other flat approach plate 23 for a resist-removing process. Thus,unnecessary parts of the resist film are removed from the opposite sideedge parts of the substrate M.

Then, in step 11-5, the removing nozzles 30 are returned to their homepositions, and the approach stage moving mechanism 60 separates theapproach stage 20 from the substrate M. Subsequently, the chuckoperating mechanism 50 raises the chuck 10, turns the chuck through 90°in a horizontal plane, and lowers the chuck 10 to mount the substrate Magain on the support table 22 in step 11-6. In step 11-7, the nozzlemoving mechanism 40 moves the removing nozzles 30 for scanning from oneto the other side of the substrate M to measure the width of thesubstrate M, and the sensors 70 send detection signals to the CPU 80. Instep 11-8, the CPU 80 provides a control signal to control the approachstage moving mechanism 60 such that the flat approach plates 23 of theapproach stage 20 are positioned as close as possible to the oppositesides of the substrate M or are disposed in contact with the oppositesides of the substrate M.

Subsequently, the removing nozzles 30 are moved continuously from one ofthe flat approach plates 23 on one side of the substrate M to the otherflat approach plate 23 for a resist-removing process in step 11-9. Thus,unnecessary parts of the resist film are removed from the opposite sideedge parts of the substrate M.

After the completion of the resist-removing process, the removingnozzles 30 are returned to and kept at their home positions for the nextcycle of the resist-removing process. At the same time, the approachstage moving mechanism 60 separates the approach stage 20 from thesubstrate M, the chuck operating mechanism 50 raises the chuck 10 totransfer the substrate M from the chuck 10 to the carrying arms, notshown, moved into the thin film removing unit 3. Substrates aresubjected to the thin film removing process successively, and thosesteps are repeated to remove unnecessary parts of resist films from edgeparts of the substrates.

Although the thin film removing devices of the present invention hasbeen described as applied to the resist film forming/removing system forforming a photomask, the thin film removing devices of the presentinvention is applicable to removing unnecessary parts of thin films fromsquare or rectangular substrates, such as glass substrates for formingthe flat display panels of FPDs and glass substrates for forming theflat display panels of LCDs.

The thin film removing devices according to the present invention havethe following effects.

(1) The solvent can be jetted uniformly on the edge parts and thecorners of the substrate and the solution can be sucked away by the thinfilm removing device without changing modes of supplying the solvent andsucking the solution. Thus, straight parts of the thin film formed onthe substrate can be removed from the corners of the substrate and theformation of mists can be suppressed.

(2) Parts of the thin film are removed from the opposite edge parts ofthe substrate, the substrate holding means is raised, is turned through90° in a horizontal plane, the substrate holding means is lowered, andthen parts of the thin film are removed from the other opposite edgeparts of the substrate. Thus, parts of the thin film can be removed fromall the edge parts of the substrate. Since the vertically movablesubstrate holding means facilitate transferring the substrate betweenthe substrate holding means and the substrate carrying means.

(3) The suction of the thin film removing means can be enhanced by thewalls set upright on the flat approach plates of the approach stage andforming a narrow space together with the thin film removing means, partsof the thin film can be further efficiently removed from the corners ofthe substrate.

(4) The water repellent film formed at least on the surface of each flatapproach plate of the approach stage makes it difficult for the solventto adhere to each flat approach plate of the approach stage. Thus,formation of particles due to the adhesion of the solvent to thesurfaces of the flat approach plates and the separation of the driedsolvent from the surfaces of the flat approach plates can be suppressedand thereby the yield can be improved.

(5) Since the solvent and such adhered to the approach stage can beremoved through the through holes and the suction pipe, formation ofparticles due to the adhesion of the solvent to the surfaces of the flatapproach plates and the separation of the dried solvent from thesurfaces of the flat approach plates can be suppressed and thereby theyield can be improved.

(6) Since the approach stage can be positioned such that the flatapproach plates are positioned as close to the edges of the substrate aspossible or in contact with the edges of the substrate, changes in modesof supplying the solvent and sucking the solution in the boundariesbetween the substrate and the approach stage can be reduced, theefficiency of thin film removal can be further enhanced. Since theapproach stage can be positioned close to or in contact with thesubstrate in an optimum state, parts of the thin film can be furtherefficiently removed without being affected by the size of the substrateand dimensional errors in the substrate.

FIG. 9

START

9-1 SUBSTRATE MOUNTING STEP

-   -   Mount the substrate on the support table    -   Set the approach stage close to the substrate        9-2 FIRST THIN FILM REMOVING STEP

Move the removing nozzles along side edges of the substrate to removeunnecessary part of the resist film from edge parts of the substrate

9-3 DIRECTIONAL POSITION CHANGING STEP

-   -   Lift up the substrate    -   Turn the substrate through 90° in a horizontal plane    -   Mount the substrate again on the support table        9-4 SECOND THIN FILM REMOVING STEP

Move the removing nozzles to remove unnecessary parts of the resist fromother opposite side parts of the substrate

END

FIG. 11

START

11-1 SUBSTRATE MOUNTING STEP

-   -   Mount the substrate on the support table    -   Set the approach stage close to the substrate        11-2 FIRST WIDTH MEASURING STEP

Move the removing nozzles to measure the width of the substrate

11-3 FIRST APPROACH STAGE SETTING STEP

Set the approach stage close to the substrate

11-4 FIRST THIN FILM REMOVING STEP

Move the removing nozzles along side edges of the substrate to removeunnecessary part of the resist film from edge parts of the substrate

11-5 APPROACH STAGE SEPARATING STEP

Separate the approach stage from the substrate

11-6 DIRECTIONAL POSITION CHANGING STEP

-   -   Lift up the substrate    -   Turn the substrate through 90° in a horizontal plane    -   Mount the substrate again on the support table        11-7 SECOND WIDTH MEASURING STEP

Move the removing nozzles to measure the width of the substrate

11-8 second APPROACH STAGE SETTING STEP

Set the approach stage close to the substrate

11-9 SECOND THIN FILM REMOVING STEP

Move the removing nozzles along side edges of the substrate to removeunnecessary part of the resist film from edge parts of the substrate

END

1. A thin film removing method of removing unnecessary parts of a thinliquid film formed on a surface of a square substrate from edge parts ofthe surface of the substrate by jetting a solvent against the edge partsof the surface of the substrate, said thin film removing methodcomprising the steps of: mounting the substrate on a support table;positioning an approach stage having a pair of flat approach parts, oneflat approach part and other flat approach part being positionedoppositely with respect to the substrate, the pair of flat approachparts positioned close to edges of the substrate mounted on the supporttable and surfaces of the pair of flat approach parts extendingsubstantially flush with a surface of the substrate mounted on thesupport table; and jetting the solvent toward edge parts of thesubstrate mounted on the support table and sucking a solution producedby dissolving part of the thin film in the solvent by thin film removingmeans while the thin film removing means is moved from the one flatapproach part to the other flat approach part along end edges of thesubstrate.
 2. A thin film removing method of removing unnecessary partsof a thin liquid film formed on a surface of a substrate having a squareshape from edge parts of the surface of the substrate by jetting asolvent against the edge parts of the surface of the substrate, saidthin film removing method comprising the steps of: mounting thesubstrate on a support table; measuring width of the substrate by movingwidth measuring means from a position corresponding to one side of thesubstrate mounted on the support table to a position corresponding tothe other side of the same; moving an approach stage having a pair offlat approach parts, one flat approach part and other flat approach partbeing positioned oppositely with respect to the substrate, to a positionsuch that surfaces of the flat approach parts are substantially flushwith the surface of the substrate mounted on the support table, on thebasis of a width signal provided by the width measuring means to aposition close to the edges of the substrate mounted on the supporttable; and removing unnecessary parts of a thin film formed on thesubstrate from edge parts of the substrate by moving thin film removingmeans from the one flat approach part to the other flat approach part,the moving thin film removing means jetting the solvent toward the edgeparts of the substrate mounted on the support table and sucking asolution produced by dissolving part of the thin film in the solventalong edges of the substrate and the approach stage.
 3. A thin filmremoving method of removing unnecessary parts of a thin liquid filmformed on a surface of a substrate having a square shape from edge partsof the surface of the substrate by jetting a solvent against the edgeparts of the surface of the substrate, said thin film removing methodcomprising: a first substrate mounting step of mounting a substrate on asupport table; a first width measuring step of measuring width of thesubstrate mounted on the support table by moving width measuring meansfrom a position corresponding to one side of the substrate to a positioncorresponding to the other side of the same; a first approach stagepositioning step of positioning an approach stage having a pair of flatapproach parts respectively having surfaces extending substantiallyflush with the surface of the substrate such that the pair of flatapproach parts are positioned respectively close to edges of thesubstrate on the basis of a signal provided by the width measuringmeans; a first thin film removing step of jetting the solvent towardedge parts of the substrate and sucking a solution produced bydissolving part of the thin film in the solvent by thin film removingmeans while the thin film removing means is moved from the one flatapproach part to the other flat approach part along edges of thesubstrate and the approach stage; a directional position changing stepof lifting up the substrate from the support table, turning thesubstrate through 90° in a horizontal plane to change directionalposition of the substrate relative to the support table, and mountingthe substrate again on the support table; a second width measuring stepof measuring width of the substrate mounted on the support table bymoving the width measuring means from a position corresponding to oneside of the substrate toward a position corresponding to the other sideof the same; a second approach stage positioning step of positioning theapproach stage having the flat approach parts respectively having thesurfaces extending substantially flush with the surface of the substratesuch that the flat approach parts are positioned respectively close toedges of the substrate on the basis of a signal provided by the widthmeasuring means; and a second thin film removing step of jetting thesolvent toward edge parts of the substrate and sucking the solution bythe thin film removing means while the thin film removing means is movedfrom the one flat approach part to the other flat approach part alongthe edges of the substrate and the approach stage.
 4. The thin filmremoving method as set forth in claim 1, wherein a gap provided betweeneach of the pair of flat approach parts and the substrate is 1.0 mm orless.
 5. The thin film removing method as set forth in claim 4, whereinedges of the pair of flat approach parts adjacent corners of thesubstrate are concavely curved to compliment the corners of thesubstrate that are convexly curved.
 6. The thin film removing method asset forth in claim 5, wherein the gap provided between each of the pairof flat approach parts and the substrate is remains substantiallyconstant along an entire adjacent edge between the pair of flat approachparts and the substrate.